A vehicular air conditioning device, which is mounted in a vehicle, takes in inside air and outside air through an inside/outside air switching unit into an air conditioner case, and after mixing chilled air, which is cooled by an evaporator type of cooling means, and heated air, which is heated by a heater core type of heating means, inside the air conditioner case at a desired mixing ratio, the mixed air is blown selectively from a plurality of respective outlet ports disposed in the vehicle cabin interior, whereby adjustment of temperature and humidity is carried out in the interior of the vehicle cabin.
In the inside/outside air switching unit, for example, as disclosed in Japanese Laid-Open Patent Publication No 2009-073234, at a position on an upstream side of the blower, a filter is provided for removing dust and the like that is contained in the outside air. By the outside air passing through the filter, air from which dust and the like has been removed is supplied into the interior of the case. Further, by being arranged at a predetermined angle of inclination with respect to the blower that is disposed therebelow, the filter is separated with respect to an involute shaped air blowing passage disposed on the outer circumferential side of the blower, whereby blown air resistance is reduced.